Viscose manufacturing



Patented July 12, 1932 UNITED STATES PATENT. OFFICE ISAAK J. FRENKEL, OF MOSCOW, UNION OF SOGIALIST SOVIET REPUBLICS VISCOSE MANUFACTURING No Drawing. Application filed December 20, 1928, Serial No. 327,461, and in Union of Socialist Soviet Republics December 9, 1927.

My invention relates to the viscose manufacturing and has particular reference to the process of making a liquid solution of cellulose for the manufacturing of artificial silk or rayon.

the spinning The viscose which is used'for this purpose is prepared by treating a paper pulp in a solution of caustic soda with a subsequent treatment with carbon disulphide. During fixed in a bath containing a solution of sulphuric acid.

This process has a certain disadvantage that during the spinning operation such gases are liberated as hydrogen sulphide (sulphuretted hydrogen, H S), sulphur dioxide (S0 also vaporized carbon disulphide (CS All these gases are not only ill smell: ing but are also injurious to the operators health.

ties less than one per cent of the Weight of viscose (usually 03 to 0.4%).

The saltshould be added to the viscose in the process of its preparation, preferably by consists in oxidizing A free from noxious odors and of injurious 1 dissolving it in a container with caustic soda. Sodium nitrite (NaNO may be used for this purpose. r

The principal action of the nitrous acid free hydrogen sulphide with precipitation of free sulphur which partly settles on the thread giving it a brownish tint. This tint, however, disappears with a subsequent treatment of the threads.

I also found that the presence of nitrous acid considerably reduces liberation of carbon disulphide and of sulphur dioxide, so that the air in the rayon plant becomes quite gases. This causes disappearance of the eye disease weavers professional disease? The improvement in hygienic conditions, of course, tends to increase the efficiency of the operators.

process the viscose threads are I found that v of the workmen which is known asv turity of the viscose in my process is made not by titration with iodine, but by coagulaof. the free hydrogen sult1on in ammonium chloride or by quantita- V tive determination of carbon'disulphide in the xanthogenate of the viscose.

The reaction of the nitrous acid on hydrogen sulphide and on carbon disulphide is represented bythe following formulas:

I claim as my invention: 7 A method for preparlng viscose for manufacturing artificial silk, consisting inadding salts of nitrous acid to the solution of caustic alkali used in preparation of said viscose, the amount of said salts beingsuflicient to oxidize sulphurous gases formed during the process of'spinning and' fixation in acid bat In testimony whereof have aflixed my j signature.

V 'ISAAK RENKELI 

